More than half the public wants the way MPs are elected to be reformed, according to a poll.

Less than a third of adults believe their vote has made a difference in a general election, the ICM study found.

The research was commissioned by electoral reform campaign Make Votes Matter, which said the results show voters are "sick and tired" of the first past the post (FPtP) system.

It was carried out ahead of the Government's National Democracy Week, which is aimed at encouraging participation in elections.

But fewer than one in three adults, some 32%, believe British democracy is worth celebrating, according to the poll.

It found 51% of respondents are in favour of proportional representation, with 13% opposed.

A referendum on axing FPtP was held in 2011 but voters overwhelmingly backed keeping the system.

Make Votes Matter co-facilitator Klina Jordan said: "Without a hint of irony the Government, which is only in power because of a voting system that wastes millions of votes, is celebrating the state of British democracy. It would be laughable if it wasn't so hypocritical.

"This survey shows that voters are sick and tired of first past the post, which locks many out of the political system and ignores millions of voices. It is time that all parties came together to bring in proportional representation, which would make every vote matter and our society a truly democratic one."

A Cabinet Office spokesman said: "Since voters overwhelmingly backed keeping the first past the post system in the 2011 referendum on the alternative vote system, the Government has worked hard to increase participation in our democracy.

"Beginning tomorrow, the first ever National Democracy Week will support the year-long suffrage centenary celebrations, and the 90th anniversary of the Equal Franchise Act that gave equal voting rights to men and women, and build on our progress in increasing the size of the electoral register."

ICM Unlimited interviewed a representative online sample of 2,021 adults between June 8 and 11.